U.S. patent number 4,227,422 [Application Number 06/040,437] was granted by the patent office on 1980-10-14 for chain device.
This patent grant is currently assigned to Honda Giken Kogyo Kabushiki Kaisha. Invention is credited to Yoshinori Kawashima, Masaki Watanabe.
United States Patent |
4,227,422 |
Kawashima , et al. |
October 14, 1980 |
Chain device
Abstract
A chain device including a sprocket wheel, a buffer ring
provided on one side of the sprocket wheel for rotation relative
thereto, and a chain meshing therewith. The buffer ring has an
outer diameter greater than the inner-diameter dimension of a
semicircular-shaped portion of the chain which is in meshing
engagement with the sprocket wheel. Thus, when the chain and
sprocket wheel are in meshing engagement with each other, the
buffer ring is restrained and forced by the inner-diameter part of
the semicircular-shaped portion of the chain, so that the ring is
deformed into an elliptical shape. Each of the link plates which
form the chain includes a depressed portion having a curved shape
coinciding, in its radius of curvature, to the maximum radius of
curvature of the elliptically-deformed buffer ring. Such curved
shape of the depressed portion of the link plate contributes to the
improvement of durability of the buffer ring, as well as to
reduction of chain noise.
Inventors: |
Kawashima; Yoshinori (Sakado,
JP), Watanabe; Masaki (Niiza, JP) |
Assignee: |
Honda Giken Kogyo Kabushiki
Kaisha (Tokyo, JP)
|
Family
ID: |
13340910 |
Appl.
No.: |
06/040,437 |
Filed: |
May 18, 1979 |
Foreign Application Priority Data
|
|
|
|
|
May 19, 1978 [JP] |
|
|
53/67297[U] |
|
Current U.S.
Class: |
474/156; 198/834;
198/843; 474/161 |
Current CPC
Class: |
B62M
9/00 (20130101); F16H 7/06 (20130101); F16H
55/30 (20130101); F16H 2055/306 (20130101) |
Current International
Class: |
B62M
9/00 (20060101); F16H 55/30 (20060101); F16H
55/02 (20060101); F16H 7/06 (20060101); F16H
7/00 (20060101); F16H 055/30 () |
Field of
Search: |
;305/57
;74/229,219,240,243S,243R,245S,25S,245LP ;198/834,843 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Husar; C. J.
Assistant Examiner: Berman; Conrad
Attorney, Agent or Firm: Weiner; Irving M. Shortley; John L.
Yedlin; Melvin
Claims
We claim:
1. a chain device comprising:
a sprocket wheel;
a buffer ring provided on one side of said sprocket wheel for
rotation relative thereto;
a chain meshing with said sprocket wheel, said chain including a
plurality of link plate pairs;
said buffer ring having an outer diameter greater than the inner
diameter dimension of a semicircular-shaped portion of said chain
which is in mesh with said sprocket wheel; and
each of said link plates being provided with a depressed portion
having a curved shape coinciding, in the radius of curvature
thereof, with the maximum radius of curvature of the outer
periphery of said buffer ring when said buffer ring is deformed
into an elliptical shape by meshing engagement between said chain
and said sprocket wheel.
2. A chain device in accordance with claim 1, wherein:
said maximum radius of curvature is obtained in a portion of said
buffer ring corresponding to the start of meshing engagement
between said chain and said sprocket wheel.
3. A chain device in accordance with claim 1, wherein:
said sprocket wheel includes a retainer member for retaining said
buffer member; and
said retainer member is secured to at least one side of said
sprocket wheel adjacent the outer periphery of said sprocket
wheel.
4. A chain device in accordance with claim 3, wherein:
said retainer member includes a bottom portion extending at right
angles from the side of said sprocket wheel and a retaining portion
extending from the outer edge of said bottom portion in the
radially-outward direction of said sprocket wheel;
an annular space open in the radially-outward direction of said
sprocket wheel is defined by the side of said sprocket wheel, said
bottom portion of said retainer member, and said retaining portion
of said retainer member; and
said buffer ring is disposed in said annular space.
5. A chain device in accordance with claim 1, 2, 3 or 4,
wherein:
said buffer ring includes a substantially resilient radially-inner
member in the shape of a ring, and a radially-outer member formed
of a substantially elastic material.
6. A chain device in accordance with claim 5, wherein:
said radially-inner member is formed of a spring plate; and
said radially-outer member is formed of hard rubber.
7. A chain device in accordance with claim 5, wherein:
each of said link plates is substantially cocoon-shaped.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to chain devices and, more
particularly, to a chain device in which noise produced at the time
of meshing engagement of the chain with the sprocket wheel is
reduced by a buffer ring provided on one side of the sprocket
wheel.
2. Description of Related Art
A chain, such as one used for power transmission on a motorcycle or
the like and coupled to "drive" and "driven" sprocket wheels in
mesh therewith, is normally passed around such sprocket wheels in a
slack state and is suddenly brought into meshing engagement with
the sprocket wheels as it is run therebetween. Therefore, each time
the chain is forced into meshing engagement with each sprocket
wheel, impact sounds consisting mainly of high frequency components
are produced as a result of collision between the two metal parts.
A generally known means for solving such chain noise problems makes
use of the compressive deformation of rubber or the like for
absorbing shocks at the time of meshing of the chain, and
consequently wear problems are likely to arise. Particularly, when
the buffer member formed of rubber or the like is provided on the
drive sprocket wheel rather than the driven sprocket wheel by means
of baking, premature wear will result due to great load conditions,
which is a drawback from the standpoint of durability. Without such
sacrifice of durability, no reliable noise prevention effect can be
expected with such known means.
In order to afford a solution to the above problems, the present
inventors have proposed a chain noise prevention device as
disclosed in Japanese Utility Model Application No. 71829/1977
filed June 2, 1977, which corresponds to United States Patent
Application Ser. No. 909,517 filed May 25, 1978 and entitled "CHAIN
NOISE PREVENTING DEVICE." In such device, a buffer ring having an
outer diameter greater than the inner-diameter dimension of a
semicircular-shaped portion of the chain which is in mesh with a
sprocket wheel is held on one side of the sprocket wheel by a
retainer member secured to the same side of the sprocket wheel.
With such construction, at the time of meshing engagement of the
chain with the sprocket, a radially inner portion of each link of
the chain is brought into engagement with the outer periphery of
the buffer ring to alleviate the impact between the chain and
sprocket wheel. In addition, the buffer ring is deformed at such
time to absorb the impact energy, thereby further preventing the
generation of impact sounds, and reducing noise.
The present invention provides improvements over the
above-described proposed chain noise prevention device, so as to
further promote noise prevention and to enhance the durability of
the buffer ring.
Because the above-mentioned buffer ring has an outer diameter
greater than the inner diameter of a semicircular-shaped portion of
the chain which is in mesh with the sprocket wheel, with the
meshing engagement between the chain and sprocket wheel the buffer
ring restrained by the radially inner part of the semicircular
chain portion is deformed into a substantially elliptical form and
protrudes toward the non-restrained side. The buffer ring has a
base formed of a plate spring member, so that at the time of such
meshing engagement the restoring resilient force of the spring acts
in the direction of the minor axis of the ellipse. The portion of
the elliptically formed buffer ring traversing the minor axis
thereof substantially coincides with a portion of the chain
corresponding to the start of the meshing engagement between the
chain and sprocket wheel at the time of forward or reverse running.
Thus, the restoring resilient force of the buffer ring acts as a
spring load upon the mesh start portion of the chain, with the
buffer ring and chain engaging each other to produce a maximum
contact pressure therebetween in such portion. Accordingly, if
smooth engagement of the outer periphery of the buffer ring with
the inner periphery of the semicircular chain portion can be
obtained in such portion, it is possible to further reduce the
chain noise compared with prior art means, and also to minimize
wear of the buffer ring to enhance the durability thereof.
SUMMARY OF THE INVENTION
The present invention provides a chain device which includes a
sprocket wheel, a buffer ring provided on one side of the sprocket
wheel for rotation relative thereto, and a chain meshing with the
sprocket wheel and formed by a plurality of link plate pairs. The
buffer ring has an outer diameter greater than the inner diameter
dimension of a semicircular-shaped portion of the chain which is in
mesh with the sprocket wheel. Each of the link plates is provided
with a depressed portion having a curved shape coinciding in its
radius of curvature with the maximum radius of curvature of the
outer periphery of the buffer ring which is elliptically deformed
by the meshing engagement between the chain and sprocket wheel.
An object of the invention, accordingly, is to provide a chain
device in which each link plate engages the buffer ring at a
zero-degree angle or a very small angle with respect thereto, when
a radially inner portion of the link plate is brought into contact
with the buffer ring. Thus, smooth engagement of the chain and
buffer ring with each other is ensured, and noise prevention is
effectively attained.
Another object of the invention is to provide a chain device in
which, at the time of engagement between each link plate and the
buffer ring, substantially the entirety of the radially-inner
portion of the link plate engages the buffer ring so that the
contact pressure therebetween is uniformized. Thus, wear of the
buffer ring is prevented so as to further improve the durability of
the buffer ring, as well as to ensure noise prevention.
Other objects and details of the invention will become apparent
from the following description, when read in conjunction with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a longitudinally sectioned view of a sprocket wheel
provided with the device according to the invention.
FIG. 2 is a sectional view of a buffer ring.
FIG. 3 is a schematic side view showing the buffer ring in a
deformed state brought about at the time of meshing engagement of
the chain with the sprocket wheel.
FIG. 4 is a side view of a link plate forming the chain.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
With reference to FIG. 1, a sprocket wheel 1 having a number of
teeth 2 may be either a drive sprocket wheel or a driven sprocket
wheel. A retainer member 3 in the form of a ring having a stepped
portion is secured by rivets 4 to one side 1a of the sprocket wheel
1. The member 3 is formed from a steel plate with a press or the
like, and comprises a base portion 3a secured by rivets 4 to
sprocket wheel 1, an intermediate portion 3b extending from base
portion 3a at right angles to the side of sprocket wheel 1, and a
retaining wall portion 3c extending at right angles to portion 3b,
in the radially-outward direction of sprocket wheel 1. An annular
space S which is open only on the radially outer side of sprocket
wheel 1 is defined by side 1a of sprocket wheel and retaining wall
portion 3c which form both sides of space S, and intermediate
portion 3b forming the bottom thereof. Annular space S is provided
adjacent to the outer periphery of sprocket wheel 1 and inward with
respect to teeth 2, and has a constant width over the
circumferential direction of sprocket wheel 1.
A buffer plate spring ring 5 is rotatably disposed in annular space
S, and is held on the side 1a of sprocket wheel 1 by retainer
member 3. Although in the illustrated embodiment only a single
buffer ring 5 is provided on one side of sprocket wheel 1, it is
also possible to provide a pair of buffer rings on both sides of
sprocket wheel 1, i.e., to provide another buffer ring on the other
side 1b of the sprocket wheel 1 by a similarly-formed retainer
member. The buffer ring 5 has an outer diameter greater than the
inner diameter dimension of the semicircular-shaped curved portion
of chain 6 in mesh with teeth 2 of sprocket wheel 1. Thus, with
engagement of radially-inner portion 6a of the links of chain 6
with the outer periphery of buffer ring 5, a free portion 5a (FIG.
3) of buffer ring 5 not restrained by chain 6 is deformed into an
elliptical form protruding radially outwardly. The elliptically
deformed buffer ring 5 is held without being detached from sprocket
wheel 1 by retaining wall portion 3c of retainer member 3, and is
always rotatably held within annular space S.
The buffer ring 5 comprises inner and outer members 7 and 8,
respectively, as shown in FIG. 2. Inner member 7 comprises a base,
and is formed by shaping a steel spring plate into the form of a
ring. Outer member 8 is formed by shaping a material having
flexibility and elasticity, such as hard rubber or plastic, into
the form of a ring. The outer member 8 serves as a buffering
member, and is bonded to the outer periphery of spring plate base 7
by means of baking so as to cover base 7, thus forming buffer ring
5.
FIG. 3 shows the buffer ring 5 deformed into an elliptical form as
a result of meshing engagement of chain 6 with sprocket wheel 1.
Designated at O is the center (i.e., journalled portion) of
sprocket wheel 1. The radially outer side of one half 5b of buffer
ring 5 restrained by radially inner portions 6a of the links of
chain 6 has the same radius r of curvature as the inner diametrical
dimension of the links or chain. A free portion 5a of the ring
located opposite to the above-described half 5b is deformed
likewise, and therefore buffer ring 5 is deformed into an
elliptical form protruding radially outwardly. At this time, a
portion A of the chain, corresponding to the start of meshing
between chain 6 and sprocket 1, as well as a portion B
corresponding to the start of meshing at the time of reverse
running of the chain, substantially coincide with portions of the
elliptically deformed buffer ring 5 transversing the minor axis of
the ellipse. The radius r of curvature of the ellipse, i.e., the
outer periphery of buffer ring 5 corresponding to the starting
portion A or B of the meshing between the chain and sprocket, is
the maximum radius of curvature of the entire periphery of buffer
ring 5.
FIG. 4 shows an exemplary plate line 9 of the links forming chain
6. Plate link 9 has a cocoon-like shape in elevation with
depressions 10 on both upper and lower sides thereof. The
depressions 10 are formed to be of a curved shape, particularly the
depression 10a on the lower side in FIG. 4, which is adapted to
engage the outer periphery of buffer ring 5, such that the radius r
of curvature of depression 10a coincides with the maximum radius of
curvature of buffer ring 5. To simplify the manufacture of link
plate 9, the opposite side depression 10b not adapted to engage the
outer periphery of buffer ring 5 may be formed to have the same
radius r of curvature.
The value of the maximum radius of curvature can be obtained in the
following manner, by way of example.
Denoting the diameter of buffer ring 5 in the state of a true
circle as shown in FIG. 2 by D.sub.0, the length L of the outer
circumference of buffer ring 5 is:
When buffer ring 5 is restrained by chain 6 and deformed into an
elliptical shape, as shown by solid line in FIG. 3, L is:
where e is the ellipticity to give rise to the maximum radius r of
curvature and is given as: ##EQU1##
The distance H.sub.0 from the center O of sprocket wheel 1 to the
center of link plate 9 in the height direction thereof is: ##EQU2##
and the distance H.sub.1 from the center O of sprocket wheel 1 to
the center O' of the portion of the outer periphery of buffer ring
5 having the maximum radius r of curvature is: ##EQU3## In these
equations a represents the height of link plate 9, and P the pitch
length of chain 6.
From equations (1) and (2) the maximum radius r of curvature is:
##EQU4##
While the maximum radius r of curvature is theoretically obtainable
as set forth above, with the above comprising exemplary basic
calculations, in practice it is of course determined within a
permissible range, within which the function of the buffer ring can
be obtained, by taking permissible dimensional errors of the buffer
ring, sprocket wheel and chain into consideration.
The operation of the above construction will now be described
hereinbelow.
As chain 6 runs in meshing engagement with sprocket wheel 1, the
radially inner portion 6a of the links of chain 6 engages the outer
periphery of buffer means 8 because the outer diameter dimension of
buffer ring 5 is greater than the inner diameter dimension of the
links forming the semicircular-shaped curved portion of chain 6. At
the same time, the deformation of the entire shape of buffer ring 5
provided with an elastic property is always repeated, and
consequently the impact energy that would otherwise be exerted to
sprocket wheel 1 is absorbed, thus providing an additional effect
of reducing the noise, i.e., the sound of impact.
With the running of chain 6, buffer ring 5 is rotated along with
chain 6 and sprocket wheel 1 while ring 5 is displaced with respect
to them in the opposite direction within annular space S by the
reaction force to the rotation of chain 6, while maintaining the
elliptical form as a whole.
When chain 6 and sprocket wheel 1 start to mesh with each other at
the mesh start portion A or B, the outer periphery of buffer ring 5
engages the radially inner depressed portion 10a of link plate 9,
depressed portion 10a having the same radius of curvature as the
maximum radius r of curvature of buffer ring 5. Therefore, surface
contact between ring 5 and link plate 9 takes place. With such
surface contact, the load or contact surface pressure applied
between buffer ring 5 and link plate 9, which are brought into
contact with each other at the mesh start portion A (or portion B
at the time of reverse running of chain 6) with great contact
pressure due to the restoring resilient force of the elliptically
deformed buffer ring 5, is uniformized. In other words, the energy
of chain 6 at the time that chain 6 comes into meshing engagement
with sprocket wheel 1 with a great impact energy is effectively
absorbed and alleviated by engagement of the entirety of the
radially-inner surface of link plate 9 with the outer periphery of
buffer ring 5, so that wear of buffer ring 5 is effectively
reduced. Further, because the curved shape of depressed protion 10a
of link plate 9 has the same radius of curvature as the maximum
radius r of curvature of the outer periphery of buffer ring 5, link
plate 9 comes into contact with buffer ring 5 at the mesh start
portion A or B at a substantially zero-degree of angle. Thus, chain
6 is brought smoothly into engagement with buffer ring 5, so that
generation of noise can be prevented with enhanced
effectiveness.
Although there have been described what are at present considered
to be the preferred embodiments of the invention, it will be
understood that various modifications may be made therein without
departing from the spirit or essential characteristics thereof. The
present embodiments are therefore to be considered in all respects
as illustrative, and not restrictive. The scope of the invention is
indicated by the appended claims, rather than by the foregoing
description.
* * * * *